Basics of hydrocarbons for SQA National 5 Chemistry
This page covers the following topics:
2. Homologous series
3. Saturated compounds
Hydrocarbons are molecules containing only carbon and hydrogen, they are named according to the number of carbons present.
A homologous series is a group of hydrocarbons which all have the same general formula, an example of this is all alkanes have the general formula CnH2n+2 where 'n' is the number of carbons in the chain. Physical properties of molecules change up a homologous series.
When all carbon atoms are bonded to four different atoms, a molecule is considered saturated. Sometimes a carbon atom is only bonded to three different molecules and a double bond forms between two carbon atoms, this is an unsaturated molecule.
Isomers are compounds with the same molecular formula but different structural formulae, meaning they have the same atoms but are arranged differently.
Why do unsaturated molecules decolourise bromine water?
The carbon-carbon double bond opens up and the carbons form a bond with the bromine atoms. When the bromine is removed from the water it loses its brown colour.
What does the name of the compound CH₄ start with?
Which of these molecules are isomers of each other?
A and D
Which of these molecules are isomers?
B, C and D
What will the name of the compound C₄H₁₀ start with?
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